Catheters are used in a variety of applications in medicine including, for example, employing a so-called “urinary catheter” relating to draining the urinary bladder. Typically, a urinary catheter is placed through the urethra into the bladder of a subject for a variety of medical indications including relief of urinary obstruction, monitoring urine output, prevention of urinary incontinence, and the like as known in the art. Indwelling urinary catheters, designed to remain in place to drain the bladder, include at least two tubes running in parallel substantially through the length of the catheter without fluid communication between the tubes. At the distal end of a urinary catheter is a hole for urine inflow and drainage connected to one of the tubes (i.e., the so-called “drainage tube”) which can terminate at a “drainage port,” and a balloon that can be filled to secure the urinary catheter. The balloon can be filled with liquid through the other tube (i.e., the so-called “balloon tube”) which can terminate at a “balloon port.” As known in the art, each tube can terminate outside the body, or each tube can terminate within the body depending on the specific medical application. For example, the drainage tube can be linked to a urine collection bag. The balloon tube has a valve allowing instillation or removal of liquid into or from the balloon (e.g., with a syringe). As known in the art, the purpose of the inflated balloon is to keep the catheter within the bladder to drain urine. As further known in the art, the balloon diameter when inflated is larger than the urethral diameter (30F˜1 cm) preventing it from slipping out. Unlike other medical devices, urinary catheters are most commonly placed into and removed from patients by nurses, ancillary medical staff, and patients themselves. Physicians and non-physicians alike report not infrequent complications associated with placement (insertion into the patient) and removal of urinary catheters.
Unfortunately, incorrect handling and placement of urinary catheters can result in disastrous consequences. Indeed, urologists are regularly consulted to manage complications associated with misplacement of urinary catheters. The most common complication is the filling of the balloon at the tip of the urinary catheter with water despite it residing within the urethra instead of the bladder. This occurs when the medical staff does not insert the catheter up to the so-called “hub” which the merger of the balloon tube with the drainage tube outside the body. This situation can create significant urethral injury causing the patient great pain and significant bleeding and can necessitate a costly consultation by a surgical specialist. The catheter can usually be replaced after the injury, but may require invasive cystoscopy (e.g., placement of a small camera into the urethra as known in the art). Invariably, in this situation the catheter must remain indwelling for a longer than initially intended period of time to allow the urethra to heal and, in some instances, to provide pressure to halt the bleeding. Other consequences of intra-urethral balloon inflation are urinary tract obstruction, urinary tract infections, discomfort, renal failure, and death. The urethral injury incurred may result in urethral stricture or narrowing (e.g., 7% based upon a single institutional study), which can necessitate additional costly surgical interventions.
Another common complication associated with urinary catheters obtains if the catheter balloon bursts inside of the patient's bladder. This situation can arise for a variety of reasons, including filling by the medical staff in excess of the maximum volume specified by the manufacturer and/or by device malfunction (e.g., defective balloon). In such situations, the catheter “falls out”, and requires replacement. More significantly, studies have shown that upon bursting, a fragment of the balloon wall frequently breaks away from the shaft of the catheter and remains within the bladder. The balloon fragment must be retrieved, e.g., with the aid of a cystoscope by a surgical specialist. If the fragment is not removed the patient will have severe urinary symptoms, recurrent urinary tract infections, and over the long-term form stones within the bladder, all of which require further medical intervention and expense.
Moreover, when urethral catheters have a device failure, a common cause is a non-deflating balloon. Current recommendations for managing a non-deflating balloon include percutaneous or endoscopic balloon puncture, instillation of chemicals to dissolve the material comprising the balloon, or over-inflating the balloon to burst it. These techniques, while necessary, can result in balloon fragmentation, patient discomfort, bleeding, and damage to nearby organs.
Moreover, another complication of urinary catheters is the accidental removal of the catheter, while the balloon is still inflated, through the entire length of the urethra. This occurs due to a variety of causes, including catheter tubing snagging on other objects, and in patients with altered mental status who pull out the inflated catheter. This latter event can occur even with a restrained patient or in the presence of a 24-hour attendant. The result is similar to that of inflating the balloon within the urethra, but more severe as it involves the entire urethra. Further complicating premature catheter removal is the necessity to replace the catheter through an already damaged urethra, and possible disruption in some cases of a still healing surgical repair (i.e. after removal of the prostate for cancer or repair of a urethral stricture).
Another common clinical complication associated with indwelling body fluid catheters (e.g., urinary catheters) is that the fluid to be drained can become infected. For example, urinary catheters are known to be not only associated with UTI (urinary tract infection), but the catheter itself is a well-recognized risk factor for the development of a UTI. Indeed, catheter associated UTI (CAUTI) is the foremost common nosocomial (i.e., hospital acquired) infection in the US today, and CAUTI accounts for a significant proportion of health care expenditures, patient morbidity, prolonged hospital stay, and death, in US hospital patients.
In order to prevent infection from arising in and spreading from urinary catheters, a variety of procedures are routinely employed. Catheters must be placed under sterile techniques, and catheter kits with closed drainage systems to help prevent infection are often used. Also, urinary catheter manufacturers typically specify that only sterile water, and never saline, should be used to fill the catheter balloon. Manufacturers also specify that the balloon should generally always be filled with the designed amount (e.g., 10 mL) of sterile water, and not more. However, the scientific rationale for such guidelines is not well described in the literature. Indeed, a recent publication was unsuccessful in conclusively explaining whether use of saline, instead of sterile water, increases the risk of catheter malfunction. See Hui et al., Int. J. Urol. 2004, 11:845-847.
The methods and compositions provided herein address these and other problems in the art.